This invention relates to the field of devices and methods for measuring fluid flow rates. More particularly, the invention provides a heated thermocouple probe for measuring fluid flow rates in a variety of processing equipment used in effecting a chemical and/or physical change in a feed stream, e.g., single phase or two phase flow reactors featuring concurrent, countercurrent, upflow or downflow passage of fluid streams, distillation, extraction and separator units, absorbers, desorbers, etc.
Obtaining uniform flow of fluid streams within predetermined limits is an important consideration in the design of chemical processing equipment, e.g., packed bed two-phase flow reactors. Reactors of this general type are well known and are widely employed for a variety of chemical conversions such as hydrotreating, hydrocracking, dewaxing, etc., of a hydrocarbon feed. As noted in U.S. Pat. No. 4,039,430, the efficacy of a chemical reaction is dependent on the degree of uniformity of the fluid flow profile as it passes through the catalyst bed. In optimizing the design of apparatus where uniform fluid flow is desirable, e.g., the aforementioned packed bed two-phase flow reactor, it is very helpful to have an accurate understanding of the thermal mass flux conditions which prevail at various locations within the reactor.